package chap05.doublelyLink;

/**
 * Created by root on 2017/7/10.
 */

class Link{
    public long dData;
    public Link next;
    public Link previous;

    public Link(long dd){
        dData = dd;
    }

    public void displayLink(){
        System.out.print(dData + " ");
    }
}

class DoublyLinkedList{
    private Link first;
    private Link last;

    public boolean isEmpty(){
        return first==null;
    }

    public void insertFirst(long dd){
        Link newLink = new Link(dd);
        if (isEmpty()) {
            last = newLink;
        } else {
            newLink.next = first;
            first.previous = newLink;
        }
        first = newLink;
    }

    public void insertLast(long dd){
        Link newLink = new Link(dd);
        if (isEmpty()) {
            first = newLink;
        } else {
            last.next = newLink;
            newLink.previous = last;
        }
        last = newLink;
    }

    public Link deleteFirst(){
        Link temp = first;
        if (first.next == null){
            last=null;
        } else {
            first.next.previous = null;
        }
        first = first.next;
        return temp;
    }

    public Link deleteLast(){
        Link temp = last;
        if (last.previous == null) {
            first = null;
        } else {
            last.previous.next = null;
        }
        last = last.previous;
        return temp;
    }

    public boolean insertAfter(long key, long dd){
        Link current = first;
        while (current.dData != key) {
            current = current.next;
            if (current == null) {
                return false;
            }
        }
        Link newLink = new Link(dd);
        if (current == last) {
            last = newLink;
        } else {
            newLink.next = current.next;
            current.next.previous = newLink;
        }
        current.next = newLink;
        newLink.previous = current;
        return true;
    }

    public Link deleteLink(long key){
        Link current = first;
        while (current.dData != key) {
            current = current.next;
            if (current == null) {
                return null;
            }
        }
        if (current == first) {
            first = current.next;
        } else {
            current.previous.next = current.next;
        }

        if (current == last) {
            last = current.previous;
        } else {
            current.next.previous = current.previous;
        }
        return current;
    }

    public void displayForward(){
        System.out.print("List (first-->last):　");
        Link current = first;
        while (current!=null) {
            current.displayLink();
            current = current.next;
        }
        System.out.println();
    }

    public void displayBackward(){
        System.out.print("List (last-->first):　");
        Link current = last;
        while (current!=null) {
            current.displayLink();
            current = current.previous;
        }
        System.out.println();
    }
}

public class DoublyLinkedApp {
    public static void main(String[] args){
        DoublyLinkedList theList = new DoublyLinkedList();

        theList.insertFirst(22);
        theList.insertFirst(44);
        theList.insertFirst(66);

        theList.insertLast(11);
        theList.insertLast(33);
        theList.insertLast(55);

        theList.displayForward();
        theList.displayBackward();

        theList.deleteFirst();
        theList.deleteLast();
        theList.deleteLink(11);

        theList.insertAfter(22,77);
        theList.insertAfter(33,88);

        theList.displayForward();
    }
}
